2.3.0 - OnlyWorlds v2 API + Delete Element

OnlyWorlds v2 API under the hood

Every sync path now speaks the OnlyWorlds v2 API. No note-format changes -- your vault works exactly as before, but sync is faster, safer, and more honest.

• Download World is incremental. First download pulls everything; re-downloads pull only what changed (v2 change feed). Big worlds re-download in seconds.
• Upload World no longer full-replaces. Elements are created or updated individually -- elements that exist on the server but not in your vault are reported, never deleted.
• New: Delete Element. Permanently removes the active note's element from onlyworlds.com and trashes the note -- with a type-the-name confirmation.
• Link safety. A link field containing an unresolvable link is skipped (server values kept, with a notice) instead of pushing a reduced list. Element names with characters like ':' no longer break note files on Windows.
• Progress feedback. Downloading/uploading toasts with progress ticks.
• Clearer errors with the server's actual message and a link to the error docs.

Legacy endpoints fully retired; auth rides API-Key/API-Pin headers everywhere. Existing vaults work unchanged.